Method of removing aluminum halides in hydrocarbon conversion processes



Dec. 26, 1950 J. L. GROEBE ET AL METHOD OF REMOVING ALUMINUM HALIDES IINHYDROCARBON CONVERSION PROCESSES 2 Sheets-Sheet 1 Filed 001;. 23, 1945FIG.

zoEjom mzo oo Poi Q25 F I w STRENGTH OF CAUSTIC'WEIGHT NAOH IN ORlGINALSOLUTION IN VEN TORS J.L. G ROEBE FIG. 3.

E.F. DEVILLAFRANCA ATTOR N EYS Patented Dec. 26, 1950 UNITED STATESPATENT OFFICE METHOD OF REMOVING ALUMINUM HAL- IDES IN HYDROCARBONCONVERSION PROCESSES Delaware Application October 23, 1945, Serial No.624,046

11 Claims.

This invention relates to a hydrocarbon conversion process. ()ne aspectof this invention relates to the purification of fluid reactioneifiuents from hydrocarbon conversions carried out in the presnce of ananhydrous normally solid or liquid metal halide of the Friedel-Craftstype which is volatilizable or soluble in the efiluent, which effiuentscontain hydrocarbons, usually both the original and the producthydrocarbon in addition to any by-products, as well as metal halide. Amore specific aspect of this invention relates to a process wherein thereaction efiluent leaves the reaction zone in the vapor or liquid phaseand is subjected to a purification treatment to remove therefrom thevolatilized or dissolved metal halide catalyst contained therein. An-

. other aspect of this invention relates to a process have been used innumerous processes for the conversion of hydrocarbons, includingdecomposition or cracking of high-boiling hydrocarbons, isomerization oflow-boiling hydrocarbons, polymerization of olefins, disproportionation,and al kylation of alkylatable hydrocarbons, including bothisoparaffins, normal parafilns, cycloparaffins, and aromatichydrocarbons. In such processes these catalysts have been used as such,suspended in or dissolved in a reaction mixture, suspended on solidsupports such as active carbon, activated alumina or aluminous'materials such as bauxite, active silica, and various clays such asfuller's earth, kieselguhr, etc., and as separate liquids in the form ofcomplexes with organic and inorganic compounds. The more useful of theliquid complexes are those formed with parafflnic hydrocarbons,especially those formed with more or less highly branched, normallyliquid paraffin hydrocarbons boiling in the boiling ranges of thosefractions generally identified as gasoline and kerosene. In manyinstances it is desirable to have present a small amount of a hydrogenhalide, sometimes only about 0.1 to about 1 to 5 per cent by weight.This material may be present as a z result of side reactions, such aswhen water is present in a charge stock, when an organic halogencompound is present in a charge stock, when some interreaction betweenan aluminum halide and hydrocarbon takes place, or when a hydrogenhalide is deliberately added.

At the present time, hydrocarbon conversions;

efiected with the aid of aluminum chloride, or like metal halidecatalysts, are characterized by numerous troubles including corrosion,further reactions, clogging of equipment, etc., caused by the catalystpermeating the entire system. These troubles are especiallyobjectionable in those sections of the equipment which follow theconversion unit. Thus, where the efliuent is removed in the vapor phaseand where the catalyst is readil volatilizable, the effluent containssubstantial quantities of vaporized catalyst, and heretofore thiscatalyst deposits in the equipment after the converter or reaction zone.Again, where the effluent is removed in the liquid phase, it

contains substantial quantities of dissolved or tilized metal halidecatalyst from vaporous efiiuents or a. dissolved metal halide catalystfrom liquid efliuents from the reaction zone of a process using themetal halide as a catalyst.

It is still another object to remove a Friedel-l Crafts metal halidefrom a gaseous or liquid stream.

Another object is to provide an improvement in a process for theproduction of diisopropyl.

Still another object is to provide specific con ditions of operation forremoving aluminum chloride from an efiiuent by contact with an alkalimetal hydroxide solution.

Further objects and advantages will become apparent to those skilled inthe art from the accompanying description and disclosure.

In accordance with this invention a Friedel- Crafts metal halide isremoved from a fluid stream by contacting the same with an aqueoussolution of an alkali metal hydroxide such as sodium or potassiumhydroxide. In one embodiment, the efiluent from the reaction zone of ahydrocarbon conversion process containing a metal halide, such asaluminum chloride, therein is contacted or washed with an aqueoussolution of sodium hydroxide to remove the metal halide from theeffluent whereby corrosion and clogging of subsequent equipment throughwhich the efiiuent subsequently passes is prevented or minimized.Specifically, certain limits of initial concentration of the alkalimetal hydroxide in the aqueous solution used to remove the metal halidefrom either a gaseous or liquid stream have been discovered and haveheretofore been unknown and unpredictable. These limiting conditions,which quite unexpectedly show a maximum and minimum hydroxideconcentration in the aqueous solution for optimum operation of thecaustic washing process, will be discussed more fully hereinafter.

As used in this specification, caustic solution may be defined as anaqueous solution of an alkali metal hydroxide, and the caustic: washingprocess is the scrubbing, washing or contacting of an effluent with sucha solution.

. The process may be operated in either a batchwise, continuous, orsemi-continuous manner, this first being preferred. Thus, a vapor orliquid effluent leaving a continuously operated conversion zone may becontinuously passed to a caustic washing step in which a causticsolutionis being continuously recycled. When the caustic solutionreaches the minimum concentration allowable, the spent solution isdischarged from the caustic washing system and a fresh solution of therequired quantity reintroduced into the system. The treated eiiluent iscontinuously passed in the vapor or liquidv phase to subsequentequipment for further treatment.

The process of this invention is particularly applicable to thetreatment of the efiluent from the alkylation of isobutane with ethyleneto produce diisopropyl 62,,3-dimethyl butane), a. valuable blendingingredient for high octane gasolines. The invention is applicable toalkylationin general, as well as to various isomerization processes inwhich a Friedel-Crafts metal. halide catalyst is used.

An example of another eiiluent which may be treated by the presentinvention is that efiluent from the cracking of high-boiling petroleumoils to. make gasoline in the presence of aluminum chloride or the likeand hydrogen chloride.

The invention is preferably applied to a liquid eiiiuent, such as theliquid efiiuent from the alkylation of isobutane with ethylene toproduce diisopropyl in the presence of aluminum chloride-hydrocarbonliquid complex in a reaction zone. In such an application, the liquideiiluent is contacted or washed with a sodium hydroxide solution; forexample, in an absorber directly following the reaction zone.

It is well known that aluminum chloride may be dissolved in light liquidhydrocarbons and also in heavier liquid alkylates of such hydrocarbons.The conventional liquid complex catalyst employed in this alkylation ofisobutane with ethylene to produce diisopropyl contains both bound andloosely bound or unbound aluminum chloride, the latter being the activeingredient of the catalyst. This active aluminum chloride is dissolvedin the liquid hydrocarbon phase. In fact, since the liquid hydrocarbonand mixing time.

a phase contains heavy alkylate and perhaps some polymer, both of whichare excellent for the preparation of the aluminum chloride hydrocarbonliquid complex used as the catalyst, it is probable that suchhydrocarbons tend to produce catalyst by stripping or reacting with thealuminum chloride from the main catalyst phase. If this reaction wererapid resulting in immediate formation of the final liquid catalystcomplex, the complex thus formed would settle with the catalyst-phasewithin the reaction zone. This, however, is not the case, because thecompleted liquid complex requires considerable agitation Therefore, thealuminum chloride in the hydrocarbon alkylate effluent leaving thereaction zone or settling tanks following the reaction zone is in theprocess of being converted into a complex. This situation makesneutralization of the aluminum chloride verydifficult because theindividual granules of aluminum chloride are coated with an oil filmwhich is immiscible and unreactive with the sodium hydroxide solution.Caustic washing is essential to neutralize the aluminum chloride, butbecause of the above facts, such neutralization is very difficult and inmany instances requires extensive contacting equipment of higheiiiciency, such as two or three mixing pumps, or mixes in series. I

Furthermore, once the hydrocarbon protective film is destroyed, thealuminum chloride. hydrolyzes slowly before complete neutralization isachieved. It is very easy, therefore, for partiallyneutralized aluminumchloride to leave the caustic' washing step unless adequate precautionsare made to assure complete neutralization.

The above condition gives rise to phenomenon known to alkylationindustry as delayed hydrolysis. This phenomenon results in severecorrosion and plugging of lines, valves, controls, and bubble platecolumns in the downstream separation system. Aluminum chloride reactswith steel to form ferric. chloride which is very corrosive. Thus it isessential that the caustic :2 washing step be conducted under maximumefficiency conditions and the, aqueous solution v of alkali metalhydroxide, suchas sodium hydroxide, must be at optimum strengthfor'neutralizing aluminum chloride. and dissolving any sodium chlorideand Bayerite (A12O3'3H2O) formed. by the neutralization with sodiumhydroxide. Any precipitation of sodium chloride or Bayerite will.seriously impair the operation of the process. A dilute sodium hydroxidesolution would also require almost infinite contact time and expensivehigh pressure equipment (400 p. s. i. or more).

In addition to optimum caustic washing it is. desirable and usuallyessential to follow the caustic washing step with a coalescence stepcomprising passing the product stream'through a solid supported contactbed which is operated downstream from the caustic washing step.

Sand, gravel, quartz chips, etc., may be used as coalescing material,but lump or pulverized limestone is preferred. This arrangementcompletes any hydrolysis reaction by providing extensive contactsurface. Furthermore, any finely suspended caustic dronlets or aluminumchloride complex with caustic is coalesced. to a liquid phase and may bedrained from the bottom of the vessel containing the contact bed. I

Figures 1, 2, and 3-ofthe drawings show the optimum initialconcentration of sodium hydroxide inan aqueous solution to be used fortheremoval of aluminum chloride from a gaseous or vaporou's hydrocarbonstream by conversion to the AlCIs equivalent.

The curve of Figure 1 was plotted from data in column 1 of Table I. Thecurves of Figures 2 and 3 were plotted from columns 2 and "3 of Table I,respectively.

According to Figure 1, the maximum solubility of aluminum chloride in agiven quantity of sodium hydroxide solution will occur with initial ororiginal concentration of sodium hydroxide in an aqueous solution atabout 21.5 per cent by weight, or 11 mol per cent. In one respect thismeans that when a fixed quantity of caustic solution is used, i. e.,10,000 gal., that this initial concentration of sodium hydroxide in theoriginal quantity of solution should be approximately 21.5 weight percent in order that it may react with the maximum quantity of aluminumchloride before precipitation of sodium chloride occurs in thecontacting equipment. Of course, when precipitation occurs, the spentsolution is no longer used but is replaced with a freshbatch of causticsolution.

According to Figure 2, the maximum utilization of sodium hydroxide willoccur when the original caustic solution contains approximately 16weight per cent, or about 8 mol per cent, sodium hydroxide. This meansthat in consideration of the cost of sodium hydroxide only, theaforesaid strength of solution should be used in order to obtain themaximum utilization per dollar expended for hydroxide. Howeven'if thisstrength of caustic solution is used, Figure 1 indi-- cates that only 78per cent as much aluminum chloride will be dissolved in a fixed quantityor in one charge of such caustic solution before precipitation occurs ascompared with a sodium hydroxide concentration of 21.5 weight per cent.Therefore, the 16 weight per cent caustic solution will have to bedumped or replaced more frequently, necessitating additional labor costsand interruption of operations. These two items must necessarily bebalanced against savings in sodium hydroxide which will occur with the16 weight per cent solution.

Figure 3 shows that the residual strength of the spent caustic solutiondecreases rapidly as the initial concentration of sodium hydroxide inthe original caustic solution is decreased from about 27 to 21.5 weightper cent. After this point is reached, the rate of decline is less rapidand the limiting point in this direction, of course, is the minrnumconcentraton of sodium hydroxide required to perform the desiredtreating operation without excessive contacting or mixing equipment. Incommercial installations it is not economical to entertain installationof sufficie t D mps. or mixers and settling tanks to achieve goodtreating efliciency with the concentration of sodium hydroxide much lessthan 2 per cent by Weight (0.9 mol per cent). Consequently, the use ofan initial concentration of sodium hydroxide much less than 16 weightper cent is also undesirable for the above reason. It can be seen fromFigure 3 that when starting with sodium hydroxide solution of a strengthlying in the range of 8 to 11 mol per cent (16-22 wt. per cent), theamount of caustic in the spent solution lies in the range of 1.8 to 2.8per cent by weight.

When all factors are considered, preferred or optimum operatingconditions obtain when the original or initial concentration of sodiumhydroxide in the caustic solution is in a range between about 16 andabout 21.5 or 22 per cent by weight, or between about 8 and about 11 molper cent. At the high value end of this range the cost of the sodiumhydroxide for a given treating operation will be slightly higher but thefrequency of change and therefore the operating labor will be at aminimum. At the low value end of this range the cost of sodium hydroxidewill. approach a minimum whereas the operating labor at interruption ofoperation will be slightly increased.

The temperature used in the purification treatment may vary widely.Where a vaporous effluent is being treated, it is preferred to usetemperatures sufficiently high that condensation of the hydrocarbonsbeing treated is prevented but below about 200 F. However, it isperfectly possible when treating vaporous efiiuent, to operate thecaustic washing step at a temperature such that condensation, partial orcomplete, of the hydrocarbon efiiuent takes place. As will beunderstood, whether condensation takes place or not, and if so, to whatextent depends also upon the pressure maintained in the caustic washingstep. Ordinarily this pressure will be substantially the same as that inthe conversion step although it may be materially higher or lower thanthat pressure by the use of suitable pressure increasing means (e. g. apump or com ressor) or pressure reducing means between the catalyticconverter and the absorber.

The absorber or washing unit may, if desired, function as a coolerand/or a quencher for the vaporous efiiuent where the vapors are at asubstantially higher temperature than the caustic solution. Thus thequenching, i. e., rapid cooling of the hot reaction effluent, may serveto prevent reactions between the reaction products, etc.

Where a vaporous efliuent is treated in the absorber or washing unit insuch manner that condensation of hydrocarbons contained in the effluentoccurs, layer separation is allowed to take place, preferablycontinuously in any suitable manner obvious to those skilled in the art.The aqueous phase is separated from the lighter hydrocarbon phase bygravity.

Where a liquid reaction effluent is treated with a caustic solution inaccordance with the invention, the treatment may be conducted at anytemperature ranging from the freezing point of the effluent or causticsolution to about 200 F. The treatment may be conducted in any apparatusknown to be suitable for intimate liquidliquid contacting, followingwhich the separation of phases is made and the two separated phasesfurther processed as desired.

A preferred embodiment of my invention will now be discussed in somedetail in connection with the accompanying drawings which form a part ofthis application and which show an anaces-yes 7 rangement of apparatussuitable for practicing the invention. While various features of theinvention will be discussed in connection with. the reaction ofisobutane and ethylene to produce diisopropyl in the presence of analuminum chloride-hydrocarbon liquid complex as the catalyst, it isto beunderstood that the invention can be applied to other reactants and toother Fricdel- Crafts metal halide type catalysts.

Referrin now to Figure l an isobutane stream; is passed to the processthrough line Ill and a. mixture of isobutane and ethylene is passed tothe process through line H. As will be appreciated by those skilled. inthe art in a commercial plant these hydrocarbons will be. accompanied bycomparatively small amounts of other hydrocarbons.. Such hydrocarbons,however, should be present in relatively small amounts, particularlywhen they are also reactive under the reaction conditions. Thealkylati'on reaction is conducted infour reactors -ii, l3, I l, and|5,-with reactors l2 and is being operated in series and reactors id andit being operated in series, the first said set. of reactors beingoperated in parallel to the. second set of reactors. More than. two suchsets of reactors may, of course, be used if desired. Contents of eachreactor are intimately admixed by means of a stirrer 2c. The isobutanestream is. passed through lines [5 and I? in two portions.

to the bottom of each of reactors l2 and M, which 1 are the primaryreactors in each set. A catalyst stream from a common catalyst source,such as line 2!, is passed in two portions through. lines 22 and 23 tothe bottoms of reactors i2 and M.

This catalyst stream comprisesv used and freshv catalyst. Theisobutane-ethylene stream is split into six portions. To the bottom ofeach of the primary reactors i2 and I4 is added one of these portionsthrough lines 24 and 25. To the middle of each of the two primaryreactors I2 and M is added another portion through lines 28 and 21. Arecycled portion of the hydrocarbon eiilucuts of the reaction is passedthrough line. 30 and divided into two portions which are passed throughlines 3! and 32, each portion also being added to the bottom of theprimary reactors I2 and. I4.

A preferred reaction temperature for this conversion is between aboutand about 209 F., preferably about 80 to about 150 F. Whenalkylatinghydrocarbons, the activity of the cata lyst. herein described issufiiciently high that even ethylene undergoes rapid reaction withinthis temperature range. It is generally preferred to operate under apressure such that the hydro carbons are present in the reaction zonesubstantially in liquid phase and in many instances the hydrocarbonmaterial will be kept in com pletely liquid phase under the preferredreaction conditions. The flow rate of reactants to. the reaction zone ispreferably expressed in terms of amount of product produced, and when.reacting isobutane with ethylene to produce diisopropyl weprefer tooperate at fiow rates between about 0.2. and. about. 1.5 gallons oftotal allrylate. produced per gallon of catalyst" present in the reactorper hour. Thus, when reacting isobutaue and ethylem in a reactor havinga total internal volume of 1,009 gallons and with ahydrocarbon tocatalystratio within the reactor of 3:2 and a. flow rate of 1.25 gallonsof alkylate per gallon of catalyst per hour, 500 gallons of alkylate areproduced per hour.

It is preferred to have. a. volume ratio of hydro-' carbons to. catalystin the reaction. zone between.

about: 9.21 and about 1:1 and the'preferred ratio has been found to beabout 3122. When thev re.- action mixture. is maintained. intimatelyadmixed with the catalyst under the preferred conditions, thehydrocarbon phase is the continuous phase, Under these conditions thecatalyst. readily separates from the hydrocarbons and power requirementsin order to maintain a suitable intimate admixture are not excessive.However, when a greater amount. of. catalyst is. used, it has been foundthat. a phase inversion may take place with the result that the catalystphase is the continuous phase and th hydrocarbon phase thediscontinuous. phase, which is not. nearly so satisfactory. Under suchconditions it is quite difficult to obtain adequate physical separationbetween the hydrocarbon phase and the catalyst phase and a considerableamount of power is required in order to adequately mix hydrocarbons andcatalyst charged. to the. reaction zone.

As the mixture of reactants and catalyst passes up through the primaryreactors it is thoroughly admixed so that the catalyst is present inextremely small particles. From the top of each of the primary reactorsthisv intimate admixture is passed, through lines Hand 34, to the bottomof the corresponding secondary reactor. At this point the final twoportions of. the isobutanee ethylene mixture are added through lines 35.and 35. The hydrocarbon-catalyst mixture is also in timately admixed thesecondary reactors. l3 and I5 toeffect suitable reaction. Theresulting,- admixtures are passed through lines 31 and 38: to.corresponding primary settlers 40 and 4|. These settlers are preferablyvessels set on a. slope with a: solid bafile plate 42. and 43 near theinlet. and extending. about halfway up in the tank. This baflle. plateserves to distribute the incoming emulsion across the tank section,thereby;

tending to reduce the shortcircuiting effect, and:

also serves as a retainer Wall for the catalyst' which settles out. Theliquid catalyst which settles; out. is removed through lines 44 and 45.and combined to form a common catalyst source in, line. 2|. A line, 39is provided joining eifiuent lines 3'! and 38 for usev in case ofemergency if one of the settlingtanks 40 or 4| needs tov be.

taken out of. service. Ordinarily this line 39. will not be used. I

From the.- toppart of settling tanks 49 and. 4|.- a hydrocarbon mixture.is passed through lines 46 and 41 and; is combined in line 50. A substantial portion of, this combined hydrocarbon ma terial is passed throughline 5| to cooler 52' and is returned to the reactors through line 30as: previously discussed. Since this combined hydrocarbon materialstill. contains a small amount: of entrained catalyst, generally,however, not: more than about two or three to about eight or ten per.centof, the total catalyst, the remaining; portion is passed to asecondary settler 53. Since;

the catalyst which is still present: in the hydrocarbon material isquite finelydivided and represents the.- finely divided particlespresent in the;-

emulsion passed from the secondary reactors: through lines 31.- and 38,a somewhat longer settling, time is necessary in settler 53 than was;used in either settlers 4B or 4|. Catalyst which separates out is passedthrough line 54 for ad:-. mixture with the catalyst removed throughpipes:

44 and 45.

A liquid hydrocarbon material substantially free from. catalyst complexbut containing unreacted hydrocarbons, alkylate, and some dissolved or;entrained aluminum chloride is treated for 'removal "of .fll dissolved jaluminum chloride and'iother acid material. -The hydrocarbon effluentfrom settler 53 'is passed through line 55 to-caustic washing unit.58:where it is contacted with an aqueous solution of sodiumhydroxide aspreviously .described to remov the aluminum chloride, etc. Washing unit58 contains a fixed quantity of aqueous solution which is recycledthrough lines 59, 6D and Bi to line 55 and through mixing pump 51. Thehydrocarbon'efliuent and causticsolution are intimatelygmixed in pump 51and then passed to washing unit 58 for further contact and liquid phaseseparation. The initial concentration ofzisodi'um hydroxide in theaqueous solutionis about"21.5 weight per cent. After use theconcentration of sodium hydroxide decreases, and finally the aqueoussolution, becomes saturated with neutralization products, such as sodiumchloride and Bayerite. When .the caustic solution becomes saturated andprecipitation begins, the spent caustic solution is discharged from thesystem through line 59 and a fresh quantity or solution introduced intothe system through line 6|. Water and caustic or additional, causticsolution may be continuously or intermittently'added through line 6|during the washing process While a portion of the caustic solution iswithdrawn through line 59 in a similar manner. However, a completelycontinuous process is difiicult and ordinarily the caustic solution isdischarged after a certain amount of use. Preferably, a batch causticwashing process is operated. rather than a continuous process but theconcentration of sodium hydroxide is initially within the rangeof about16 and 22 weight per cent, or 8 and ll mol per cent.-

A washed hydrocarbon eflluent substantially free from aluminumrchloridefand acid material is removed -jfrom...washing :unit'. 58 and passedthrough line'62. tocoalescingiunit. 53 comprising a. solid supported bedof limestone. Entrained caustic, etc.,' iscoalesced. aspreviouslyidi'scussed and removed from coalescing unitB3 through line64. Hydrocarbon .material is passed 'from icealescing unit 63 throughline 65 to bauxite dryer 66 to remove traces of water dissolved orentrained in the hydrocarbon material.

From dryer BB hydrocarbon material is passed through line 67 toseparating means 18, which represents a series of fractionators or othersimilar equipment for separating the hydrocarbon components from thehydrocarbon material. A diisopropyl fraction is separated and removedthrough line 12 as a product of the process. Unreacted isobutane isseparated and returned to the process through line l3. Normal butane,which will include that initially accompanying the charge stock and anynormal butane formed by isomerization during the alkylation process, maybe separated and discharged through line 14. One or more other alkylatefractions may also be recovered, as through line 15. Any undesired lightgases may be discharged through line '16.

In making the original batch of catalyst, kerosene or other hydrocarbonmay be added through as a high-aluminum chloride complex such as 10previously discussed, may 'be intimately mixed with it. The resultingfortified catalyst is-passed through -line 85' and returned toifpipe' 2|wherein it is' mixed-witli the recirculated catalyst. Since suchtreatment tends to increase the total volume of catalystavailablei-twill generally b found necessary to maintain a desired volume ofcatalyst by withdrawal oi" material from line 84 through line 86.' Whenit is desired to use a hydrogen halide in preparing the catalyst suchmaterial maybe'added through either of lines or-82. Ins'uch instances itis often not necessary to add hydrogen halide to .the reaction system;Howeve'rfif it isfound desirable at any time to add a hydrogen halide tothe reaction system; any desired portion may be added through line 81 tothe catalyst present in line 2|. While an aluminum halide, namelyeitheraluminum chloride, bromide orvery infrequently, iodide, is mostcommonly used as the catalyst in carrying out our'invention, other metalhalides of the Friedel-Crafts type and which are normally either liquidor solid, usually the latter, may be' used; Examples are the chlorides,bro mides or iodides of the following metals:

Z'inc' Titanium Tin .Iron Arsenic Boron Antimony Beryllium zimc im,

Although this invention has been described with particular reference-tohydrocarbon conversion processes-, especially the alkylation-ofisobutane with ethylene to produce diisopropylgthe optimum conditions'ofoperating a caustic washing processare equally applicable to'the removalofa metal halide from any gaseous or liquid stream composedof'su-bstantially inert material. It -will be understood tha't variousmodifications may occur to those skilled in'the art in thedetailedembodiments described above without departing from the scope of theinvention.- 7

We claim: 1. In a hydrocarbon con-version proces's' where-i inconversion is effected in the presence of an aluminum chloride catalystand wherein a vaporous eilluent from a reaction zone contains a minoramount of aluminum chloride, the improvement which comprises contactingsaid v-aporous eflluent containing aluminum chloride with an aqueoussolution of sodium hydroxide 01' an initial concentration between about8 and 11 mole per cent at a temperature below 200 F. under conditionssuch that said vaporous effluent is rapidly cooled and condensed and asubstantial portion of said aluminum chloride is removed, continuing thecontacting with additional effluent at gradually decreasingconcentration of sodium hydroxide in said solution as reaction withmetal halide progresses until the stage of imminent precipitation isreached, and thereafter replacing the spent caustic solution with freshsolution of the aforesaid concentration.

2. In a process for the alkylation of isobutane with ethylene to producediisopropyl comprising passing ethylene and isobutane to a reaction zonein the presence of an aluminum chloride alkylation catalyst underalkylation conditions such that diisopropyl is produced and separatingdiisopropyl from the resulting efliuent as a product of the process, theimprovement which comprises contacting said resulting efliuentcontaining aluminum chloride with a solution of alkali metal hydroxideof an initial concentration in the range of 8 to 11. mol per cent, andcontinuing the. contacting with. additional efiluent at graduallydecreasing concentration of alkali metal hydr xide as. reaction withaluminum chloride progresses, whereby aluminum chloride is removed fromthe efliuent withv optimum utilization of alkali.

\3. The process of claim 2 wherein said alkali metal hydroxide is sodiumhydroxide.

4. In a hydrocarbon conversion process whereinconversion is effected inthe. presence of an aluminum chloride catalyst and, wherein an effluentfrom the reaction zone. contain a minor amount of aluminum chloride, theimprovement which comprises contacting said effluent containing aluminumchloride with an. aqueous solution of sodium hydroxide of an initialconcentration in the range of 16 to 22.- per. cent by weight, continuingthe contacting with additional, efiluent at gradually decreasingconcentration. of sodium hydroxide in said solution as. reactionwith.aluminum, chloride progresses whereby aluminum, chloride is removed fromthe effluent with optimum utilization of alkali, and replacing the spentcaustic solution with v freshsolution oi the aforesaid concentrationWhen the spent solution contains an amount of sodium hydroxide in therange of 1.8 to 2.8 per cent by weight but before precipitation occurs.

5. The process of claim 4 in which the initial concentration of sodiumhydroxide is about 11 mol per cent.

a- The process of claim. 4. in which, the initialconcentration of sodiumhydroxide is about 8 mol percent.

'7. In a hydrocarbon conversion process wherein; conversion is eficctedin, the presence. of a 'Friedel-Crafts type metal halid catalyst andwherein an efiluent'from a reaction zone contains a; minor amount of themetal halide, the improvement which. comprises. contacting said eilluentcontaining the metal halide with an aqueous solution. of. an alkalimetal hydroxide. of an initial concentration in the range of 8 to 11 molper cent, continuing the contacting, with. addi- I2 tional eflluent. atgradually decreasing concentration of alkali metal hydroxide. in saidsolution as reaction with metal halide progresses until the stage ofimminent precipitation is reached, and thereafter" replacing the spentcaustic. solution with fresh solution 0! the aforesaid concentration.

3. They process. of claim 7 in which said metal halide catalyst is analuminum chloride-hydrocarbon complex.

9'. The process of claim 7 wherein the contact of. said efiluent withsaid aqueous solution is in the liquid phase.

10. The process: or claim 7' wherein said alkali metal hydroxide issodium hydroxide,

11. The. process for removing aluminum chloride from av relatively inertliquid material which comprises contacting said relatively inertmaterial containing aluminum chloride with an aqueous solution of sodiumhydroxide of an. initial concentration in the. range of 8' to 11 mol percent, continuing the contacting with additional eflluent at graduallydecreasing concentration of alkali metal hydroxide in said solution asreaction with metal halide progresses until th stage of imminentprecipitation is reached and thereafter replacing the spent causticsclutlon with fresh solution of the; aforesaid concentration.

JOHN- L. GROEBE. EDWARD F. or: VILMFRANCA.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,304,290 Peski. Dec. 8, 1942,2,313,660. Montgomery Mar. 9, 1943 2,320,293 Ostergaard May 25, 194.32,340,600 Lamb; et a1. Feb. 1, 1.9 4 2,363,264 Rosen Nov. 21., 19442,407,873: Evering et a1 Sept.. 17, 1946 2,433,482 Roberts Dec. 3.0,1947 Certificate of Correction Patent No. 2,535,735 December 26, 1950JOHN L. GROEBE ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Column 4, line 29, for mixes read mixers; column 5, lines 1 and 2,strike out by conversion to the A161 equivalent and insert the sameafter Table I and before the period, in line 4:;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 20th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

1. IN A HYDROCARBON CONVERSION PROCESS WHEREIN CONVERSION IS EFFECTED INTHE PRESENCE OF AN ALUMINUM CHLORIDE CATALYST AND WHEREIN A VAPOROUSEFFUENT FROM A REACTION ZONE CONTAINS A MINOR AMOUNT OF ALUMINUMCHLORIDE, THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID VAPOROUSEFFUENT CONTAING ALUMINUM CHLORIDE WITH AN AQUEOUS SOLUTION OF SODIUMHYDROXIDE OF AN INITIAL CONCENTRATION BETWEEN ABOUT 8 AND 11 MOLE PERCENT AT A TEMPERATURE BELOW 200*F. UNDER CONDITIONS SUCH THAT SAIDVAPOROUS EFFUENT IS RAPIDLY COOLED AND CONDENSED AND A SUBSTANTAILPORTION OF SAID ALUMINUM CHLORIDE IS REMOVED, CONTINUING THE CONTACTINGWITH ADDITIONAL